Coordination-assembled Nanoarchitectonics of Antioxidant Peptide and Flavonoid Myricetin for Sustainably Scavenging Free Radicals

Oxidative stress can lead to permanent and irreversible damage for cellular components, and even cause cancer and many diseases. Therefore, the development of antioxidative reagents is a significant strategy for alleviating chronic diseases and maintaining the redox balance. Small-molecule bioactive compounds have exhibited huge therapeutic potential in antioxidant and anti-inflammatory. Myricetin (Myr) as well-defined natural flavonoid, has drawn wide attention on highly effective antioxidant, anti-inflammatory, antimicrobial, and anticancer activities. Especially at antioxidation, Myr is capable of not only chelating intracellular transition metal ions for removing reactive oxygen species (ROS), but also activating antioxidant enzymes and related signal, achieving sustainable scavenging radical activity. However, Myr possesses poor water solubility, which limits its bioavailability for biomedical application, even clinical therapeutic potential. The endogenous antioxidant peptide glutathione (GSH) plays a direct role on antioxidant in cells and possesses good hydrophilicity and biocompatibility, but is easily metabolized by enzyme. To take advantages of their antioxidation activity and overcome the above-mentioned limitations, the GSH, Zn2+ and Myr are selected to co-assemble into Myr-Zn2+-GSH (abbreviated as MZG nanoparticles or nanoarchitectonics). Thence, this study offers a new design to harness stable, sustainable antioxidant nanoparticles with high loading capacity and bioavailability, good biocompatibility for optimizing antioxidant to protect cells from oxygenated damage.

Angiotensin I-Converting Enzyme (ACE-I) Inhibition and Antioxidant Peptide from a Squilla Species

Background: Oratosquilla woodmasoni is one of the marine squilla species which is found in the entire Asia-Pacific region. This current study assesses the species as the main basis of both ACEi and antioxidant peptide. Objective: To isolate the ACEi peptide derived from O. woodmasoni and examine its ACE inhibition along with antioxidant potential. Methods: The squilla muscle protein was hydrolysed using alcalase and trypsin enzymes for 12 hours and tested for DH. The hydrolysates were examined for their ACEi activity, and then the best hydrolysate was sequentially purified in various chromatographical methods. The purified peptide was studied for anti-oxidant and functional properties, followed by amino acid sequencing. The purified peptide was also evaluated for its toxicity by in vitro cell viability assay. Results: The DH% was found to be 47.13 ± 0.72 % and 89.43 ± 2.06 % for alcalase and trypsin, respectively. The alcalase 5th-hour hydrolysate was detected with potent activity (65.97 ± 0.56 %) using ACEi assay and was primarily fractionated using ultrafiltration; the maximum inhibitory activity was found with 77.04 ± 0.52 % in 3-10kDa fraction. Subsequently, the fraction was purified using IEC and GFC, in which the AC1-A2 fraction had higher antihypertensive activity (70.85 ± 0.78 %). The non-toxic fraction showed hexapeptide HVGGCG with molecular weight 529 Da with a great potential of antioxidant activity along with functional property. Conclusion: This peptide could be an alternative as a nutraceutical for both ACE inhibition and antioxidant.